Women aged 15-24 years account for 20% of the 1.7 million new HIV-1 infections annually around the world. That means every week nearly 6,000 young women become infected with HIV-1.
As there is no vaccine for HIV-1, the CDC and WHO recommend daily, oral pre-exposure prophylaxis (or PrEP) for individuals who are at high risk of acquiring HIV. Current approved PrEP is called Truvada, which consists of 2 antiretroviral drugs: tenofovir and emtricitabine (FTC), and requires a doctor's prescription. If taken consistently, Truvada PrEP reduces the risk of HIV infection more than 95%!
But inconsistency in taking the daily pills is the biggest challenge for PrEP efficacy. Therefore, scientists developed long-acting nanoparticles for injection and sustained release of the antiretroviral rilpivirine (RPV LA).
In our study, we evaluated the ability of a long-acting nanoparticle formulation of the antiretroviral drug rilpivirine (RPV LA) to inhibit vaginal transmission of WT or drug-resistant HIV-1 in female mice with human immune systems.
We found the following:
- We achieved biologically relevant concentrations of RPV in the plasma and female genital tract of female humanized mice after a single injection of RPV LA.
- RPV LA initially inhibited WT HIV-1 in 67% of animals but, due to delayed infections when drug concentrations waned, ultimately prevented infection in 41% of animals.
- RPV LA prevented transmission of Y181C HIV-1 (3-fold resistant to RPV) in 100% of animals. (Presumably, RPV prevented Y181C HIV-1 more effectively than WT HIV-1 because the mutant had reduced transmission.)
- RPV LA did not prevent Y181V HIV-1 (25- to 30-fold resistant to RPV) in any animals.
- In animals that did become infected despite a single dose of RPV LA PrEP, significant frequencies of additional NNRTI resistance mutations were NOT selected, as measured by single-genome sequencing.
Read our study here.
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